External Rc; Uart; Touch Sensor - Espressif Systems ESP32 Hardware Design Manuallines

2. SCHEMATIC CHECKLIST AND PCB LAYOUT DESIGN

2.2.1.6 External RC

External resistors and capacitors should be placed close to the chip pins, and there should be no vias around the
traces. Please ensure that 10 nF capacitors are placed close to the pins.

2.2.1.7 UART

The series resistor on the U0TXD line needs to be placed as close as possible to the chip so that the U0TXD traces
on the top layer are as short as possible.

2.2.1.8 Touch Sensor

ESP32 offers up to 10 capacitive IOs that detect changes in capacitance on touch sensors due to finger contact or
proximity. The chip's internal capacitance detection circuit features low noise and high sensitivity. It allows users to
use touch pads with smaller area to implement the touch detection function. Users can also use the touch panel
array to detect a larger area or more test points.
In order to prevent capacitive coupling and other electrical interference to the sensitivity of the touch sensor system,
the following factors should be taken into account.
Electrode Pattern
The proper size and shape of an electrode improves system sensitivity. Round, oval, or shapes similar to a hu-
man fingertip is commonly applied. Large size or irregular shape might lead to incorrect responses from nearby
electrodes.
Note:
The examples illustrated in Figure
Espressif Systems
Figure 16: A Typical Touch Sensor Application
17 are not of actual scale. It is suggested that users use a human fingertip as reference.
19 ESP32 Hardware Design Guidelines V2.1